This project will examine the effect of exercise training on functional status in patients with HIV wasting; and the effect of exercise on abdominal visceral fat and insulin resistance in patients with HIV-associated fat redistribution. In the past several years, we have shown that 1) one bout of hard exercise does not raise HIV RNA levels; 2) progressive resistance exercise (RE) leads to increase in lean mass, comparable to that seen with growth hormone or androgen therapy; 3) RE leads to fat loss in normal- weight subjects, but to fat (and total mass) gain in wasted subjects; 4) in patients with fat redistribution, aerobic plus resistance exercise (ARE) leads to significant decline in trunk fat mass without loss of lean body mass or peripheral fat mass. In addition, we have preliminary evidence that 5) RE improves functional status via increases in strength and lean mass; 6) the protein metabolic response to one bout of hard exercise differs substantially between wasted and non-wasted patients; and 7) that this response can be used to predict who will benefit from RE with a gain in lean mass. Thus exercise potentially offers singular advantages in treatment and prevention of both wasting and abdominal obesity in HIV infection. The long-range goal of this research is to develop practical ways of using exercise to prevent and treat body composition abnormalities caused by HIV infection. We propose to recruit 100 patients with HIV infection with either wasting or fat redistribution, and enroll them in a long-term, randomized, outpatient study of exercise and diet. The major outcomes for the wasting group will be increased in lean mass and functional status, and whether the protein metabolic response to one bout of acute exercise predicts the response to RE. For the fat redistribution group, the expected outcomes are a decrease in abdominal visceral ft, improved insulin resistance, increased muscle glucose transporter-4 (GLUT-4) levels, and improved lipoprotein status.